Vitamin B12 Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin B12, including details on cyanocobalamin, benefits, supplements, deficiency, side-effects, sources.

Effect of folic acid and B vitamins on risk of cardiovascular events and total mortality among women at high risk for cardiovascular disease: a randomized trial.

Albert CM, Cook NR, Gaziano JM, Zaharris E, MacFadyen J, Danielson E, Buring JE, Manson JE

Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 900 Commonwealth Ave E, Boston, Massachusetts 02215-1204, USA. calbert@partners.org

CONTEXT: Recent randomized trials among patients with preexisting cardiovascular disease (CVD) have failed to support benefits of B-vitamin supplementation on cardiovascular risk. Observational data suggest benefits may be greater among women, yet women have been underrepresented in published randomized trials. OBJECTIVE: To test whether a combination of folic acid, vitamin B6, and vitamin B12 lowers risk of CVD among high-risk women with and without CVD. DESIGN, SETTING, AND PARTICIPANTS: Within an ongoing randomized trial of antioxidant vitamins, 5442 women who were US health professionals aged 42 years or older, with either a history of CVD or 3 or more coronary risk factors, were enrolled in a randomized, double-blind, placebo-controlled trial to receive a combination pill containing folic acid, vitamin B6, and vitamin B12 or a matching placebo, and were treated for 7.3 years from April 1998 through July 2005. INTERVENTION: Daily intake of a combination pill of 2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12. MAIN OUTCOME MEASURES: A composite outcome of myocardial infarction, stroke, coronary revascularization, or CVD mortality. RESULTS: Compared with placebo, a total of 796 women experienced a confirmed CVD event (406 in the active group and 390 in the placebo group). Patients receiving active vitamin treatment had similar risk for the composite CVD primary end point (226.9/10,000 person-years vs 219.2/10,000 person-years for the active vs placebo group; relative risk [RR], 1.03; 95% confidence interval [CI], 0.90-1.19; P = .65), as well as for the secondary outcomes including myocardial infarction (34.5/10,000 person-years vs 39.5/10,000 person-years; RR, 0.87; 95% CI, 0.63-1.22; P = .42), stroke (41.9/10,000 person-years vs 36.8/10,000 person-years; RR, 1.14; 95% CI, 0.82-1.57; P = .44), and CVD mortality (50.3/10,000 person-years vs 49.6/10,000 person-years; RR, 1.01; 95% CI, 0.76-1.35; P = .93). In a blood substudy, geometric mean plasma homocysteine level was decreased by 18.5% (95% CI, 12.5%-24.1%; P < .001) in the active group (n = 150) over that observed in the placebo group (n = 150), for a difference of 2.27 micromol/L (95% CI, 1.54-2.96 micromol/L). CONCLUSION: After 7.3 years of treatment and follow-up, a combination pill of folic acid, vitamin B6, and vitamin B12 did not reduce a combined end point of total cardiovascular events among high-risk women, despite significant homocysteine lowering. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000541.

Published 7 May 2008 in JAMA, 299(17): 2027-36.
Full-text of this article is available online (may require subscription).

Articles on Vitamin B12 published 3 April 2008:

Gene identification for the cblD defect of vitamin B12 metabolism.   N Engl J Med, 358(14): 1454-64.

BACKGROUND: Vitamin B12 (cobalamin) is an essential cofactor in several metabolic pathways. Intracellular conversion of cobalamin to its two coenzymes, adenosylcobalamin in mitochondria and methylcobalamin in the cytoplasm, is necessary for the homeostasis of methylmalonic acid and homocysteine. Nine defects of intracellular cobalamin metabolism have been defined by means of somatic complementation analysis. One of these defects, the cblD defect, can cause isolated methylmalonic aciduria, ... [Abstract] [Full-text]

Microcompartments for B12-dependent 1,2-propanediol degradation provide protection from DNA and cellular damage by a reactive metabolic intermediate.   J Bacteriol, 190(8): 2966-71.

Salmonella enterica grows on 1,2-propanediol (1,2-PD) in a coenzyme B(12)-dependent fashion. Prior studies showed that a bacterial microcompartment (MCP) is involved in this process and that an MCP-minus mutant undergoes a 20-h period of growth arrest during 1,2-PD degradation. It was previously proposed that growth arrest resulted from propionaldehyde toxicity, but no direct evidence was presented. Here, high-pressure liquid chromatography analyses of culture medium were used to show that the ... [Abstract] [Full-text]

Articles on Vitamin B12 published 1 April 2008:

Head group modulated pH-responsive hydrogel of amino acid-based amphiphiles: entrapment and release of cytochrome c and vitamin B12.   Langmuir, 24(8): 4280-8.

The present study describes the rational design and synthesis of amino acid-based amphiphilic hydrogelators, which were systemically fine-tuned at the head group to develop pH-responsive hydrogels. To understand the basic structural requirements of a low molecular weight amphiphilic hydrogelator, 10 analogous amphiphiles based on L-phenylalanine and L-tyrosine with structurally related head group were synthesized. Among them, three with quaternary ammonium substitution at the head group formed ... [Abstract] [Full-text]

Articles on Vitamin B12 published 19 March 2008:

A disulfide-stabilized conformer of methionine synthase reveals an unexpected role for the histidine ligand of the cobalamin cofactor.   Proc Natl Acad Sci U S A, 105(11): 4115-20.

B(12)-dependent methionine synthase (MetH) from Escherichia coli is a large modular protein that is alternately methylated by methyltetrahydrofolate to form methylcobalamin and demethylated by homocysteine to form cob(I)alamin. Major domain rearrangements are required to allow cobalamin to react with three different substrates: homocysteine, methyltetrahydrofolate, and S-adenosyl-l-methionine (AdoMet). These same rearrangements appear to preclude crystallization of the wild-type enzyme. ... [Abstract] [Full-text]

Articles on Vitamin B12 published 3 March 2008:

Plasma vitamin B12 concentrations and the risk of colorectal cancer: a nested case-referent study.   Int J Cancer, 122(9): 2057-61.

In this nested case-referent study, we related plasma concentrations of vitamin B12 to the risk of colorectal cancer, taking into consideration prediagnostic plasma folate and total homocysteine concentrations. Subjects were 226 cases and double matched referents from the population-based Northern Sweden Health and Disease Study. Follow-up times from recruitment to diagnosis ranged from 0.1 to 12.7 years, with a median of 4.2 years. Plasma vitamin B12 concentrations were inversely associated ... [Abstract] [Full-text]

Articles on Vitamin B12 published 27 December 2007:

The conformational coupling and translocation mechanism of vitamin B12 ATP-binding cassette transporter BtuCD.   Biophys J, 94(2): 612-21.

ATP-binding cassette transporter BtuCD mediating vitamin B(12) uptake in Escherichia coli couples the energy of ATP hydrolysis to the translocation of vitamin B(12) across the membrane into the cell. Elastic normal mode analysis of BtuCD demonstrates that the simultaneous substrate trapping at periplasmic cavity and ATP binding at the ATP-binding cassette (BtuD) dimer proceeds readily along the lowest energy pathway. The transport power stroke is attributed to ATP-hydrolysis-induced opening of ... [Abstract] [Full-text]

Articles on Vitamin B12 published 12 December 2007:

Magnetic field effect studies indicate reduced geminate recombination of the radical pair in substrate-bound adenosylcobalamin-dependent ethanolamine ammonia lyase.   J Am Chem Soc, 129(50): 15718-27.

The apparent conflict between literature evidence for (i) radical pair (RP) stabilization in adenosylcobalamin (AdoCbl)-dependent enzymes and (ii) the manifestation of magnetic field sensitivity due to appreciable geminate recombination of the RP has been reconciled by pre-steady-state magnetic field effect (MFE) investigations with ethanolamine ammonia lyase (EAL). We have shown previous stopped-flow MFE studies to be insensitive to magnetically induced changes in the net forward rate of C-Co ... [Abstract] [Full-text]

Articles on Vitamin B12 published 6 December 2007:

Modern society and prospects of low vitamin B12 intake.   Ann Nutr Metab, 51(5): 468-70.

BACKGROUND: Vitamin B(12) deficiency can occur in individuals with dietary patterns that exclude animal foods and patients who are unable to absorb vitamin B(12 )in food. MATERIAL AND METHOD: Our clinic serves a high-income population living in Southern Israel. We hypothesize that a tendency to decrease of level of vitamin B(12) in our population is caused by a premeditated decrease in consumption of animal products. We analyzed 512 medical histories of patients undergoing blood tests for ... [Abstract] [Full-text]

© 2004-2008 Vitamin B12 Research Today. All Rights Reserved.